There is a huge industry developed around the demand to drill multiple, spaced holes (through or non-through) in substrates such as electronic wafers, thin film electronics, organic packaging substrates, glass, silicon wafers, sapphires or the like. These holes or patterned drillings may be used for electrical connections, filtration, cytology, bioassays, chemotaxis, or particle monitoring and have diameters that commonly lie in the micron range. Not only must the holes be identical to each other in diameter but also must be placed at precise locations and with the right geometry with respect to the substrate or adjacent holes.
Generally, such drilling machines see movement in all three axes simultaneously. The substrate is positionally moved in the horizontal x axis beneath a drill that plunges in the z vertical axis after the drill has been positionally moved in the Y horizontal axis atop the substrate by a gantry unit. Drilling is initiated once the substrate is in the proper position as indicated by a set of metrology positioning sensors on the machine and at least one pressure foot has secured the PCB substrate on the x axis table to the z axis drill unit. This positioning prior to drilling occurs extremely rapidly by computer control, cycling up to thousands of times per minute. Pursuant to Newton's third law of motion, each of these three positioning or drilling movements creates a reactionary force in the structure of the PCB substrate drilling machine. Since it is this machine that metrology positioning sensors are coupled to, the settling time or lag for the PCB substrate to be positioned within the acceptable ranges of the feedback sensors is slowed by the effects of the reactionary forces, thus slowing the positioning process and adding slight inaccuracies in the positioning and eventual placement of the holes in the PCB.
Prior art PCB substrate drilling systems rely on the use of a massive, heavy machine base to minimize these reactionary forces coupled with light moving masses, however, these reactionary forces still inherently reside in the machine and serve to limit the speed and accuracy at which the machine can function. When drilling micro holes or vias of 100 microns or less in diameter at a rates higher than 15 cycles per second, the positioning accelerations increase to meet the point to point positioning commands and the disturbances that are injected into the heavy machine base cause the settling time at the end of each positioning to become longer thus cancelling out any move time reduction gained by the improved acceleration of the lighter moving masses. Additionally, the sensors operate with moderately large settling windows (in the 0.1 micron range) in the x and y axes. These prior art solutions that increase the mass of the machine base (reaction mass) and make the moving masses lighter do not completely address the root cause of the problem—that the unitary base design supports both the metrology system and the drilling system.
Henceforth, a PCB substrate drilling machine with improved accuracy and speed, faster and deeper drilling depth (increased PCB substrate stack heights), longer drill bit life, less drill bit breakage and a higher machine throughput would fulfill a long felt need in the substrate drilling and surface patterning industry. This new invention utilizes and combines known and new technologies in a unique and novel configuration to overcome the aforementioned problems and accomplish this.